Horizontal Tube Evaporator
It consists of a vertical cylindrical shell incorporating a horizontal square tube bundle at the lower portion of the shell. Channels are provided on either ends of the tube bundle for introduction of steam and withdrawal of condensate. The shell is closed by dished heads at both the ends. A vapour outlet is provided on the top cover and a thick liquor outlet is provided at the bottom. Feed point is located at a convenient point. In this evaporator, steam
is inside the tube and the liquor to be concentrated surrounds the tubes. Steam which is admitted through one of the steam chests/channels and flows through the tubes. Steam gets condensed by transferring its latent heat and the condensate is removed from the outlet provided at the bottom of the opposite steam chest. This type of evaporator is shown in Fig.
Fig. Horizontal tube evaporator diagram
Heat given out by the condensing steam will be gained by the solution in the evaporator and the solution boils. Vapours formed are removed from the top, while the thick liquor is removed from the bottom. In this evaporator as evaporation occurs outside the tubes, it eliminates a scale formation problem inside the tubes.
Advantages of Horizontal Tube Evaporator :
- Very low head room requirements and large vapour-liquid disengaging area.
- It is not suited for salting and scaling liquids as deposits form on the outside of the tubes.
Applications of Horizontal Tube Evaporator:
It is commonly used for small capacity services and for simpler problems of concentrations, i.e., for processes wherein the final product is a liquor, such as industrial sirups.